Valsi 7.5kw gen. The output voltage varies about 30 % with or without a load. the generator seems to be running at a constant speed. the speed of variation is a pproximately 1/2 hz. It would appear a voltage regulator problem If there is a charge for this service notify me and get my approval before proceeding

Do you know how to test automotive electrical circuits with a voltmeter ? Your alternator is not getting power where ? The only place it gets power is at heavier gage wire on the back of the alternator . Battery positive voltage . The two wires in the connector are from the PCM / ECM - engine computer . Your vehicle has what is called a smart charging system .
https://www.motor.com/magazinepdfs/042010_09.pdf

Your best bet ,take it to a qualified repair shop.

Circuit Description
The generator provides voltage to operate the vehicle's electrical system and to charge its battery. A magnetic field is created when current flows through the rotor. This field rotates as the rotor is driven by the engine, creating an AC voltage in the stator windings. The AC voltage is converted to DC by the rectifier bridge and is supplied to the electrical system at the battery terminal.
When the engine is running, the generator turns on a signal to the generator from the powertrain control module (PCM), turning the regulator on. The generator's voltage regulator controls current to the rotor, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine is started, the regulator senses generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the regulator varies the field current by controlling the pulse width. This regulates the generator output voltage for proper battery charging and electrical system operation. The generator F terminal is connected internally to the voltage regulator and externally to the PCM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the PCM that a problem exists. The PCM monitors the generator field duty cycle signal circuit.

This vehicle also has Load Shed System

Electrical Power Management
Electrical power management (EPM) is used to monitor and control the charging system and alert the driver of possible problems within the charging system. The EPM system makes the most efficient use of the generator output, improves the battery state-of-charge (SOC), refer to Battery Description and Operation , extends battery life, and manages system electrical loads. EPM has also been know as "load management" or "load-shed" in the past.
EPM performs the following 3 functions:
• Monitors battery voltage and estimates battery SOC
• Takes corrective actions by boosting idle speed, reducing system electrical loads, and/or adjusting the generator regulated voltage control (RVC).
• Perform diagnostics and informs the driver of charging system malfunctions
The EPM algorithm is run any time the dash integration module (DIM) is awake, which includes engine running, key on, accessory mode, and retained accessory power (RAP). During this time the DIM continuously estimates the battery SOC based on battery voltage, estimated net amp hours, refer to Battery Description and Operation , battery capacity, initial SOC, and estimated battery temperature. Estimated battery temperature is a calculation based on key off time, engine run time, and the temperature reading provided by the engine control modules (ECM) air intake temperature or HVACs outside air temperature.
When the EPM algorithm is running, the DIM calculates the net charge rate on the electrical system by making constant voltage measurements. It uses the measurements to calculate the charge rate in amp/hours. If the DIM detects a negative charge rate, equal to a discharge from the battery, EPM can request up to 3 levels of idle boost from the ECM, when the vehicle is in park or neutral, as well as up to 2 levels of load shedding for a total of 5 levels of corrective action to maintain proper vehicle electrical system operation.
The DIM sends a serial data request to the PCM/ECM to increase the idle speed. The PCM/ECM then adjusts the idle speed by using a special program and idle speed ramp calculations in order to prevent driveability and safety concerns. The idle speed boost and cancel function will vary from vehicle to vehicle and from one moment to another on the same vehicle. This happens because the PCM/ECM responds to changes in the inputs from the sensors used to control the powertrain. In order to maintain Idle quality the ECM may not enter idle boost for up to 120 seconds, unless there is a manual change in throttle position. There is no set time limit for the idle decrease when the criteria has been met to exit idle boost, unless there is a manual change in throttle position.
Important: The DIM also has responsibility for requesting up to 3 levels of idle boost from the ECM for the HVAC system based upon head pressure, vehicle speed, and engine running. EPM has priority over the HVAC system when requesting idle boost. However, idle boost will be maintained at the level the HVAC system requires, even though the exit criteria has been met for EPM.

Low voltage of genset will affect the use of generator set, which is one of the common faults. This article will guide you to learn the factors that affect the voltage of generating set.

1. The unstable speed of the engine causes the unstable voltage of the generator set.
2. If the load on the generator set is too large, the voltage will be unstable.
3. The damage of the voltage regulator components of the generator causes the unit's voltage instability.
4. The poor circulation of the fuel pipe of the genset causes the unstable speed of the engine, which causes voltage instability.


https://www.dieselgeneratortech.com/diesel-generators/how-to-deal-with-low-voltage-of-diesel-generator.html

Which module ?

B1318 Battery Voltage Low Audio Control Module REFER to Section 414-00 . B1318 Battery Voltage Low DSM REFER to Section 414-00 . B1318 Battery Voltage Low DVD Player REFER to Section 414-00 . B1318 Battery Voltage Low Instrument Cluster REFER to Section 414-00 . B1318 Battery Voltage Low RCM REFER to Section 414-00 . B1318 Battery Voltage Low Satellite Radio Receiver REFER to Section 414-00 . B1318 Battery Voltage Low SJB REFER to Section 414-00 .
According to this charging system isn't working correctly ! This is a computer controlled charging system .
Principles of Operation
The powertrain control module (PCM) controlled charging system determines the optimal voltage setpoint for the charging system and communicates this information to the voltage regulator. This system is unique in that it has 2 unidirectional communication lines between the PCM and the generator/regulator. Both of these communication lines are pulse-width modulated (PWM). The generator communication (GEN COM) line communicates the desired setpoint from the PCM to the voltage regulator. The generator monitor (GEN MON) line communicates the generator load and error conditions to the PCM. The third pin on the voltage regulator, the A circuit pin, is a dedicated battery voltage sense line.
The charging system voltage is controlled by the PCM. The generator charges the battery and at the same time supplies power for all of the electrical loads that are required. The battery is more effectively charged with a higher voltage when the battery is cold and a lower voltage when the battery is warm. The PCM is able to adjust the charging voltage according to the battery temperature by using a signal from the intake air temperature (IAT) sensor. This means the voltage setpoint is calculated by the PCM and communicated to the regulator by a communication link.
The PCM simultaneously controls and monitors the output of the generator. When the current consumption is high or the battery is discharged (the PCM recognizes this and increases the output of the generator to accommodate), the system is also able to increase the idle speed to increase the charge.
To minimize the engine drag when starting the engine, the PCM does not allow the generator to produce any output until the engine has started. The PCM then progressively increases the output of the generator.
The PCM turns the charging system warning indicator off after the engine is started and illuminates it under fault conditions (when the generator is not generating the correct amount of current with the engine running). The charging system warning indicator is also illuminated by the PCM whenever the key is ON with the engine OFF.
This is a System 4 charging system, which uses the GEN MON and GEN COM lines to control and monitor the charging system through the PCM. System 4 charging systems are virtually identical in design and therefore, share the same diagnostics. The circuit numbers and colors may be different, but the functions are the same.

It could be several things but it sounds like it just running too slow. I would the engine rpms first. Depending if is a two pole or four pole and if your 60hz or 50 Hz on the needed unloaded rpms.

Example: 2 pole 60 hz. Engine needs to be running at 3600 rpm loaded and 3750 rpm unloaded; unless, it has a fuel saving mode.
A 4 pole 60 hz would running half this rpm. The 2 pole producing 50hz would have the engine running at 3000 rpm loaded (about 3100 rpm unloaded)

Now in order for the 50 hz system to produce the same output voltage it requires a different alternator than the 60 hz version; otherwords, You simply can't convert a 60 hz to 50 hz version without changing the alternator by changing the engine speed.

On the engines carb. is a governor rod should connect to the front case of the engine. This rod should have an adjustment to slow the engine speed. BUT,,, are you reading the generator unloaded or without any thing plunged into it? Once you have the generator loaded with a device, the voltage should drop to a constant 240vac. 150 rpms should not make that big a difference on the voltage output, and if running under load the RPM's should drop also..

How long have you had this generator?
Has the generator worked on all of these loads before?
Model 5500 is a 5500 Watt generator which could easily be 5500 watts (Peak) and not continuous.

Your AC is an inductive load.
Your lights are resistive loads

An inductive load can cause issues when starting due to an increased current demand at start up that some generators cringe under. Do the lights flicker or are they stable? I'd say your diodes on your stator are working if you have light stability but you haven't provided nearly enough information for a detailed solution.

I'm sure you have enough voltage but you aren't getting enough current to run specific loads. How many watts is your AC? How many watts for your microwave? Both of these units demand a great deal of energy to run and when you place too much demand on your generator, it will choke it out and eventually, will cause damage to the generator. You may consider getting a beefier generator with a greater amount of wattage output.


Seeing these specs online and noting what you are trying to run, you have an undersized generator and need to get one that can produce a greater amount of running wattage (as well as peak wattage).

try adjusting the gen voltage at no load to run at 240 volts
when the load comes on it will drop back to 220-235 volts
check the load output from the inverter as 2.5 kv is nearly 80% of the genset duty cycle
4.5 KV is start up KV and the duty KV is around 3..8 kv not the plated 4.5 kv
to get constant 4.5 kv you will need a 5.5-6 kv unit
if the current draw from the inverter is excessive , the engine may not have enough in reserve to over come the load and will not pick up the rpms
take the gen set and the inverter to a shop that has a calibrated load bank to test accurate power output to determine if the engine needs an overhaul

Good Luck with that...but if engine runs and there is no output voltage, that generally means that the stator needs to serviced or replaced (likely as pricey as a new genny).

I’m happy to assist further over the phone at https://www.6ya.com/expert/robert_aad3edb7dfa380b9

Hi,
The engine should run at 3750 rpm at no load. If that's OK then you may need to troubleshoot the capacitor inside the end of the generator opposite the rope. Since the thing has been stored for some time you may just need to flash the field of the generator to restore the residual magnetism in the rotor. The easiest way to do this is thru the 110 outlet but it's a little dangerous. Plug an old lamp cord into the outlet, start the generator, and momentarily connect a 9 volt dry cell to the wires, then shut the generator down and see if there is 110 when you restart it.
Regards,
Carl

Both the Hz and the voltage will be wrong if the engine speed is low. You need to use either a DMM with a HZ function to set the engine speed so that you get 61.5 Hz at no load, or use a tachometer to set the no load speed to 3750 rpm.

Carl